Tivo Roamio Pro only shows 6.38 hrs on the time line.

I have a TiVo Roamio Pro. I down loaded all shows of 24, cut the ads, beginning and credits. I ended up with a 7hr 58 min programs. I pushed the program back to tivo. On the green time line it only showing 6 hrs and 38 minutes. Why would it only showing the 6 hrs and 38 mins?